During the E3 2018 we saw lots of Kingdom Hearts 3 Trailer! in fact, there are 3 of them however we never got to see any glimpse of the much anticipated Final Fantasy VII Remake.
So during an interview with The Verge, the game director Tetsuya Nomura who is directing both titles assured fans they are in development of the game in parallel with KH3.
Tetsuya Nomura's statement in the interview:
He also explained the delay of Kingdom Hearts 3 to 2019 claiming it was because more time was needed:
Tetsuya Nomura also shared some information on hes works ethics and his love of creation for the games.
So that's it! it's up to you if he is just pandering to the fans or that they really are in development and not some internal politics.
Final Fantasy VII Remake is in development for PS4 while Kingdom Hearts III releases on Jan 25, 2019 for Asia with a western release set on January 29, 2019 for PS4 and Xbox One

So during an interview with The Verge, the game director Tetsuya Nomura who is directing both titles assured fans they are in development of the game in parallel with KH3.

Tetsuya Nomura's statement in the interview:
We are developing [Final Fantasy VII] in parallel, and it’s not just in the early concept stages. We are actually in development. So right now, it’s like I’ve been putting in 100 percent into Kingdom Hearts, 100 percent into Final Fantasy VII, 100 percent into Kingdom Hearts… just going back and forth. It’s just like [working on] two titles is just going to be one [after Kingdom Hearts III’s launch]. That’s pretty much how I see it.

He also explained the delay of Kingdom Hearts 3 to 2019 claiming it was because more time was needed:
We were told by many people, including hardware manufacturers, sales teams, marketing teams, that it just wasn’t good timing in the year. For Kingdom Hearts III, the Western offices requested to release the game as simultaneously as possible between Japan and America, so we no longer were able to just think about Japanese issues and retail situations.
When we looked toward that, we were told that the best timing after all of that would be the tail end of January. We, of course, considered maybe speeding up the development to release earlier than we were told that it wasn’t good, but the development team said, no, we can’t do that. We could delay it, but we can’t make it any sooner. If we are to also potentially delay the release date, then we could have that extra time to work on the game a little more. It kind of just all worked together for us to decide on this date.

Tetsuya Nomura also shared some information on hes works ethics and his love of creation for the games.
I don’t get fatigued by that at all. It’s really fun for me to do. I actually don’t like human relationships more than just work, so I just want to focus on work and creating things, if I don’t have to deal with human relationships. It’s actually a little bit easier for me to do than not working. I do need fans to play my games, to be able to create it, and so fans are definitely a factor to motivate me to keep on going.
So that's it! it's up to you if he is just pandering to the fans or that they really are in development and not some internal politics.
Final Fantasy VII Remake is in development for PS4 while Kingdom Hearts III releases on Jan 25, 2019 for Asia with a western release set on January 29, 2019 for PS4 and Xbox One